A scanning transmission electron microscope (STEM), a transmission electron microscope (TEM), or the like (hereafter, collectively referred to as (S)TEM) is used to observe the internal structure of a minute region of a substance. To observe the interior of a sample with one of these electron microscopes, a method is generally known. In this method, a sample sliced so thin that a charged particle beam can traverse is placed on a mesh sample support with a large number of holes; and a transmitted charged particle beam image is acquired with a detector disposed on the side opposite the electron source side with respect to a sample surface. In this configuration, however, a sample is suspended over the mesh hole area and thus it is difficult to prepare a sample such that an intended observation target is positioned over the mesh hole area. To cope with this, Patent Literature 1 proposes an electron detector that enables direct placement of a sample for observation with an electron microscope.
As well as a charged particle beam microscope, an optical microscope can also be used as a means for observing a minute region of a substance. Use of an optical microscope makes it possible to acquire the color information of a sample that theoretically cannot be acquired with an electron microscope. Optical microscopes are designed to irradiate a sample with white light or specific light and form an image from transmitted light having color information, absorbed into or emitted from the sample. By applying this, for example, introducing a specific stain into a biological cell sample, a specific region in the cell can be stained; therefore, a distribution of stained regions and non-stained regions can be visualized by extracting associated color information. This technique is in wide use, especially, in the fields of pathological diagnosis and life science.
With a charged particle beam microscope, color information cannot be acquired but high-resolution observation of a minute region that is difficult with an optical microscope can be performed. In addition, a charged particle beam microscope makes it possible to obtain information reflecting a density difference in a sample as well.